There exist many types of manual and automatic swimming pool cleaners on the market. Automatic pool cleaners can be the built-in type or use an umbilical attachment and use suction, water pressure, or robotic devices to perform their cleaning tasks. These generally operate on their own using suction or water pressure, scrubbing brushes, filters, or water jets to keep the floors and walls clean. They are effective in removing both particulate and large debris. Manual pool cleaners are mostly mounted to long poles and require vigorous back and forth or circular scrubbing of the surfaces by hand to be useful. They can range from vacuum-type cleaners to water brooms, wall brushes, and hand mitts. In a comprehensive pool maintenance program, routine use of both automatic and manual methods is required to keep the surfaces clean and tidy.
Disadvantages of most automatic cleaners are that they do not scrub the surfaces of the swimming pool's walls, that they can have their movement range limited by the length of electrical cords and hoses, and that they may need additional pumps or plumbing to be installed. While robotic cleaners generally do a good job of scrubbing and debris removal, they require more maintenance of internal pumps and filters, typically should be removed before swimming to prevent cord damage, and are quite costly. Manual cleaners operation can be time consuming, monotonous, and cumbersome. Some manual devices also require regular replacement of filters or parts, which adds to costs, and may be limited to relatively short use times by their rechargeable batteries. Both the automatic and manual methods of cleaning are ineffective and inadequate once calcifications have started to accumulate.
Inevitably, even a well cared-for and scrubbed pool will eventually begin to develop calcium deposits. Swimming pool scale, which primarily consists of calcium carbonate, typically builds up fastest on the sidewalls and waterline areas where evaporation occurs, and also on steps, metal hand rails, and water features. Once the scale appears, it is very tenacious and difficult to remove. This requires additional expense in materials, labor, time, and sometimes environmentally caustic measures to clear it away.
To treat most visible scale buildup, common methods include draining the pool or spa, blasting the surfaces with abrasive powder and power-washing. These methods can be expensive requiring costs of refilling the pool, new chemicals, and the service expense. There also are environmental concerns with the powder overspray, noise during the pumping of the water, power washing, or powder spraying, and in dumping thousands of gallons of pool water and chemicals out into the surroundings.
Other methods of cleaning scale buildup involve using disposable products such as enzyme cleaners, pumice stones and cleaning blocks, acids, stain and phosphate removers, algae and metal treatment chemicals. Pumice stones or scrub brushes can be used in conjunction with muriatic acid; the acid is applied to the limescale for a certain amount of time, then scrubbed to remove the buildup. This method is not only difficult to accomplish on sidewalls and various surfaces that have the build up, but can be hazardous to a user's lungs, skin, eyes, and mouth due to the harsh nature of the acid. The acid can cause pitting of metal surfaces. Transporting and home storage of this toxic and dangerous chemical is another troubling aspect to consider. Moreover, even with intense scrubbing of the encrusted surfaces with acid and mechanical contact by stone or brush, it is not an effective or efficient means to remove the scale. The toxic sludge eventually works its way into the pool water, which can leave mounds of sediment on the pool bottom and water chemistry changes that need to be dealt with.
The use of ultrasonics in cleaning began in the 1950s, primarily in industrial applications, e.g., for manufacturing in the medical, automotive, aircraft, and munitions fields. As its popularity grew, so did its applications and usage. Ultrasonics was found to be very effective in removing surface contaminants while being non-toxic and non-harmful to that which was being cleaned. In a process called cavitation, ultrasonic waves travel through water or fluid and the vibrations tear at the fluid creating very small bubbles which are formed due to alternating pressures. When these bubbles implode, they release immense temperatures and pressures in a high velocity jet-like focus onto the surface they are directed at. Because of their small size and high energy, they can break up the contaminants on surfaces in normally difficult areas to access and clean. Ultrasonic technology can be used to clean various nonporous surfaces of dust, dirt, rust, oil, grease, carbon, limescale, bacteria, algae, wax, pigments, and other buildup.
Some pool cleaning assemblies use ultrasonic generators that are built into automatic pool cleaners. The combination of ultrasonic waves, rotating brushes, and suctioning capabilities provides increased efficacy in cleaning contaminated surfaces and hard to reach areas. However, these devices are expensive, difficult to handle, and not portable.
U.S. Pat. No. 6,259,653 describes a portable, diver-operated, encapsulated underwater ultrasonic cleaner for removing rust, scale, paint, and marine growth from underwater surfaces. It is advantageous in its design to clean underwater surfaces. However, it only operates underwater, not at or above the waterline where the most visible calcium deposits form. Additionally, it is a large device, and would be impractical for small-scale residential or commercial use from both economic and maneuverability standpoints.
Also described in the art are various hand held ultrasonic cleaning devices which are used for removing soils and stains from household items and clothing (WO 2003033179 A1, EP1143841 (A2), US 20020189635 A1, EP1232026 B1, US 20050150066 A1, CN 105755728 A, US 20050120756 A1, US 20050284190 A1), and for removal of horny substances from skin (WO 2009048271 A1), and cordless ultrasonic dental scalers for use on dental patients (U.S. patent application Ser. No. 11/624,675). These portable devices all utilize ultrasonic wave generation for removal of unwanted buildup of various types, but none are suitable for use in a swimming pool.
Thus, a heretofore unaddressed need exists in the industry to address the aforementioned deficiencies and inadequacies.